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V-253102

CAT II (Medium)

If the Trivial File Transfer Protocol (TFTP) server is required, the TOSS TFTP daemon must be configured to operate in secure mode.

Rule ID

SV-253102r1134939_rule

STIG

Tri-Lab Operating System Stack (TOSS) 4 Security Technical Implementation Guide

Version

V2R5

CCIs

CCI-000366

Discussion

Restricting TFTP to a specific directory prevents remote users from copying, transferring, or overwriting system files.

Check Content

Note: If TFTP is not required, it should not be installed. If TFTP is not installed, this rule is not applicable.
 
Determine if TFTP server is installed with the following command:
 
$ sudo dnf list installed | grep tftp-server 
tftp-server.x86_64 x.x-x.el8
 
Verify that the TFTP daemon, if tftp.server is installed, is configured to operate in secure mode with the following command:
 
$ grep -i execstart /usr/lib/systemd/system/tftp.service
ExecStart=/usr/sbin/in.tftpd -s /var/lib/tftpboot
 
If TFTP is installed and is not documented with the information system security officer (ISSO) as an operational requirement, this is a finding.

Note: The "-s" option ensures that the TFTP server only serves files from the specified directory, which is a security measure to prevent unauthorized access to other parts of the file system.

Fix Text

Configure the TFTP daemon to operate in secure mode with the following command:
$ sudo systemctl edit tftp.service
 
In the editor enter:
[Service]
ExecStart=/usr/sbin/in.tftpd -s /var/lib/tftpboot
 
After making changes, reload the systemd daemon and restart the TFTP service as follows:
$ sudo systemctl daemon-reload
$ sudo systemctl restart tftp.service